Homeland Security Investigations Special Agent James Haynes, center, announces the arrest of 71 individuals as part of Operation Caireen, a sweeping investigation into the anonymous trading of child porn over the Internet, during a news conference, Wednesday, May 21, 2014, in New York. Haynes is joined by Queens District Attorney Richard Brown, far left, Staten Island District Attorney Daniel Donovan, second left, Brooklyn District Attorney Kenneth Thompson, second right, and Manhattan District Attorney Cyrus Vance, far right. Jason DeCrowAP

Homeland Security Investigations Special Agent James Haynes, center, announces the arrest of 71 individuals as part of Operation Caireen, a sweeping investigation into the anonymous trading of child porn over the Internet, during a news conference, Wednesday, May 21, 2014, in New York. Haynes is joined by Queens District Attorney Richard Brown, far left, Staten Island District Attorney Daniel Donovan, second left, Brooklyn District Attorney Kenneth Thompson, second right, and Manhattan District Attorney Cyrus Vance, far right. Jason DeCrowAP

Never miss a local story.

While investigators assigned to track down child sex predators seek out and arrest people for possessing or distributing pornography — their priority also is to locate and rescue the children who appear in the videos and pictures that the suspects possess and trade with each other, officials said.

A look at the Castillo case, coupled with explanations by U.S. officials about efforts to combat child pornography, offer details about the federal strategy to prosecute child sex predators and rescue minors.

Though U.S. officials declined to discuss the Castillo case because it’s still under investigation, or provide specific details about overall investigative strategies, the criminal complaint filed in the Little Havana case holds some clues.

The Castillo case began earlier in the year when an investigator checked the sharing of child pornography on an online network known as Ares, according to a criminal complaint filed by a special agent of Homeland Security Investigations, a unit of U.S. Immigration and Customs Enforcement.

Eventually, the investigator tracked down the Internet Protocol address to the one-story house in Little Havana, according to the complaint.

On Oct. 15, U.S. Magistrate Judge Edwin G. Torres issued a warrant authorizing the search of the residence, according to the complaint.

Six days later, at about 6:10 a.m., Homeland Security Investigations special agents and other law enforcement officers arrived at the address.

Agents learned that four people lived in the house. Two were present and a third came in shortly after the operation began. The fourth, Castillo, had just left for work.

In a search of the house, agents found a computer with movie files depicting child pornography.

The titles of the videos listed in the complaint described the content: “10 yrs Asian girl drugged and f*****,” and “Girl 8 years old masturbates watching porno.”

The three residents in the house told agents that Castillo used the computers. Agents called him and he returned to the house where he confessed that he had downloaded the movies and videos, according to the complaint.

Castillo, 61, is now awaiting trial in Miami federal court after pleading not guilty to child pornography charges on Nov. 10.

Among federal tactics used to track down child predators are concerted efforts to locate and seize voluminous amounts of child pornography including movies, pictures and videos — both as evidence and to locate victims.

In fiscal year 2015, HSI nationwide analyzed more than 7.5 petabytes of data equal to 127.5 million hours of music, 150 million file cabinets filled with documents or more than 1 trillion pages of text, officials said.

Also in 2015, officials said, HSI special agents made 2,394 arrests nationwide, and identified or rescued 1,004 victims.

“Rescuing a victim is the ultimate goal,” one official said. “It’s probably the biggest satisfaction for the agents.”

In a recent case that drew publicity, Homeland Security Investigations special agents rescued two children — an infant and a toddler — whom a child predator had been sexually abusing in Central Florida.

Benjamin Cuadrado, who pleaded guilty in January to child pornography charges, was sentenced to 80 years in the federal penitentiary.

The Cuadrado case grew out of an investigation that started in Miami Beach. Cuadrado lived in Lakeland, near Tampa.

Child pornography has skyrocketed because of advances in technology.

“Twenty years ago you shot pictures and you had to take them to your local drugstore to get them developed,” said Nestor Yglesias, spokesman for ICE HSI. “If you took that roll of film to get developed, the person behind the counter would take your name and your phone number. If he found anything illicit or questionable, he had to call law enforcement. Next thing you’d be getting a knock on the door from law enforcement asking what this questionable material is on your roll of film.

“Nowadays, technology has taken such a turn that it’s basically a gold mine for child predators because they can literally turn something around in a matter of seconds, produce it, upload it and share it. And next thing you know, the picture’s being shared a couple of hundred times in a few hours.”

Officials said law enforcement action has been hampered by technology because predators can hide or disguise online activity. They use encrypted Internet chat rooms to prevent investigators from detecting their activities.

“Now there’s a forum in which you can talk to like-minded individuals all around the world,” another official said. “And we’re even seeing in some instances that because of that, very, very young children are being molested in real time on camera.”

One of the reasons money rarely changes hands is the fear of detection because online payment usually involves a record that can be traced.

The development of smartphones, many with sophisticated video streaming features, has added another tool for predators and made the job of law enforcement officials more difficult.

“Basically today, what 20 years ago would have been regarded as a supercomputer is now in your hands with the smartphone,” said Al Deangelus, group supervisor for Homeland Security Investigations Cyber Group in Miami. “They have magnified the problem for us.”

Smartphones also have become a tool in predators’ arsenals.

“Predators are able to reach out to kids so much easier using different aliases, posing themselves as a child on different applications,” Deangelus said. “They’ll send out 500 to 1,000 messages in a day in the hope of getting one or two children to respond.”

Officials who were interviewed for this report said parents should play a major role in the war against child predators.

One official urged parents to periodically check their children’s smartphones to look for any signs they have been approached by child predators or are exchanging or storing lewd photography.

“Parents need to watch certain things,” one official said. “Sometimes the signals are as simple as a child who might be very outgoing, next you know your child is more introverted.”

Other indicators, the official said, include changes in personality or personal hygiene, or if the child receives expensive gifts from an unknown source.

Homeland Security Investigations offers several programs to educate parents about the dangers of child predators.